Fresh water, although abundant, is often not located in sufficient quantity near population centers, agricultural production centers, or other users. For example, as population centers grow, and human populations become more geographically concentrated, local sources of potable water may be insufficient to accommodate the growing needs. Often, alternative sources of fresh water may need to be transported over intervening bodies of seawater.
The present inventor has disclosed an offshore fresh water reservoir system and method in U.S. Pat. No. 8,322,294, to Bowhay, which is hereby incorporated by reference in its entirety, wherein freshwater effluent may be captured and retained in a floating reservoir disposed in the ocean, for example. Advantages of such a system will be apparent to persons of skill in the art. For example, the system may be used to capture fresh water that would otherwise become mixed with ocean water. Also, the fresh water is retained in an offshore facility, thereby avoiding the costs of developing a land-based reservoir and preserving land space. It is contemplated that the offshore reservoir may provide a fresh water secondary reserve that may be used to replenish or maintain water levels in existing conventional reservoirs.
Shortages of fresh water, e.g., potable water and/or water for agricultural uses are being encountered more often due to demands from an increasing population, and the growing concentration of the population in large metropolitan areas. It has been estimated that by the year 2050, some four billion people will be facing sever water shortages. Such water shortages are not limited to underdeveloped countries. People living in southwestern states in the United States, for example, could be facing severe freshwater shortages by 2050, or even earlier. Although most of the Earth's surface is covered by water, less than two percent of the surface water is fresh water, i.e., water having relatively low concentrations of dissolved salts and other total dissolved solids. Shortages of fresh water are further compounded by waste and poorly managed water supplies.
A significant fraction of the human population is located near the ocean or other major bodies of salt water. Salt water is generally not potable, of course, although large quantities of fresh water regularly flow into seawater bodies. Typically, the availability of fresh water is seasonal, and seasonal water forecasting is an important undertaking for most water supply systems. During times of high water flow, fresh water may be abundantly available to fill local needs, but when the water flow drops off, severe fresh water shortages can occur. It would be useful to store fresh water, for example, river effluent from periods of high water flow, for use during times of low water flow.
Also, in certain regions near bodies of salt water and without an adequate fresh water source, water desalination plants are used to extract fresh water from the salt water body. In order to run the desalination plants at peak efficiency, while ensuring a stable supply of fresh water, it is desirable to have a reservoir to temporarily store the fresh water that is produced, for purposes of load leveling and to accommodate periods of equipment maintenance, for example.
However, there remains the problem of efficiently and reliably transporting fresh water, for example, fresh water stored in off-shore reservoirs or fresh water located a distance from the users. Fuel gasses, such as methane or natural gas, are also often available in significant quantities in sea beds. Such fuel gasses may also need to be efficiently transported long distances to be available to end users. In certain aspects of the disclosed invention, both water and gasses may be beneficially and efficiently transported together.